Well water in Shelter Island, New York
In Shelter Island, 3% of 128 tested well samples exceeded the EPA limit for nitrate (10 mg/L), based on public data from USGS Water Quality Portal.
1,425 test results across 12 contaminants from at least 35 wells, 1933 to 2025; iron has the most at 288. Data refreshed September 3, 2026.
Compiled by Nick at Well Water Nerd from public records. How these pages are built
What individual samples found
Each row summarizes every public sample for that contaminant inside Shelter Island. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.
| Contaminant | Above limit | Samples | Detected | Median | Highest | Limit |
|---|---|---|---|---|---|---|
| Nitrate 1974 to 2023 | 128 | 80% | 1.2 | 34.9 | 10 mg/L EPA limit | |
| Fluoride 1971 to 2025 | 81 | 23% | 0 | 2 | 4 mg/L EPA limit | |
| Copper 1971 to 2018 | 70 | 7% | 0 | 0.15 | 1.3 mg/L EPA limit | |
| Arsenic 1971 to 2006 | 17 | 53% | 0 | 1 | 10 ug/L EPA limit | |
| Lead 1971 to 2006 | 10 | 60% | 0 | 0 | 15 ug/L EPA limit | |
| Iron 1969 to 2025 | no limit | 288 | 95% | 285 | 25,400 | 300 ug/L nuisance level |
| Manganese 1969 to 2025 | no limit | 287 | 75% | 30 | 3,970 | 300 ug/L health guideline |
| Chloride 1933 to 2025 | no limit | 282 | 100% | 16.5 | 14,700 | 250 mg/L nuisance level |
| Sodium 1969 to 2025 | no limit | 259 | 100% | 11 | 7,620 | 20 mg/L health guideline |
Sampled fewer than 10 times, too few to summarize: Uranium (1), PFOA (1), PFOS (1).
Over time
Share of samples above the limit by period. A cell needs ten samples to show; a comparison needs twenty in each period. Later periods sample fewer wells, and often the ones already known to have a problem.
| Contaminant | before 2000 | 2000s | 2010s | 2020s |
|---|---|---|---|---|
| Nitrate | 2%107 samples | n/a | 6%17 samples | n/a |
Closer than the town
See the sampled wells near your address
The same records, drawn around one point: which wells within a few miles were sampled and what they found, how deep the wells next to you were drilled, and any leaking tank or cleanup site within a mile.
Check my addressWhat this means
The contaminants most often above their limit here are nitrate (3% of 128 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.
Iron, Manganese, and Chloride are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.
What to test for in Shelter Island
- 1Nitrate3% of 128 local samples were above the limit.
- 2Coliform bacteriaRecommended for every private well, every year.
- 3ChlorideDetected in 100% of local samples.
- 4IronDetected in 95% of local samples.
- 5ManganeseDetected in 75% of local samples.
- 6Volatile organic compounds (VOCs)1 hazardous waste site on record locally.
- 7Metals panel1 hazardous waste site on record locally.
Test your Shelter Island well for nitrate, coliform bacteria and chloride
Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.
Order the Tap Score well water test kit, from $209Already tested? Upload the report
Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.
Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.
Affiliate links: the merchant pays us a commission and the price is the same for you. It does not change what the data above says. As an Amazon Associate we earn from qualifying purchases.
Where to get a well tested in New York: certified labs, state programs and prices.
Already have results back? Get your lab report read against the Shelter Island numbers, $29. Every line explained, ranked by what matters, with the fix for each.
Wells in Shelter Island
1,211 domestic wells in Shelter Island are on record with the state. the typical well is 53 feet deep (one in ten goes past 87 feet).
Find your own well's report
The state keeps the driller's report for most wells drilled since 1984. It tells you how deep your well is, where bedrock starts, and how much water it makes, which decides what treatment can work.
- Open NYSDEC water well completion reports and choose Water Well.
- The report lists depth, depth to bedrock, cased depth, yield and the driller.
Drillers have filed reports with the state since April 2000; a well drilled before then usually has no record.
The rock under Shelter Island
Northern Atlantic Coastal Plain aquifer system
Semiconsolidated sand. Coastal plain sands like these give steady yields at moderate depth. Salt water and sodium are the usual issues near the coast, and nitrate where the water table is shallow; arsenic and radon from bedrock are less common.
Classification from the USGS Principal Aquifers of the United States (national map, 2003 edition, GIS release 2015), read at the town centroid. A single well can sit in a different unit, especially near a boundary.
Official help in New York
Two places to start that are not selling anything: the state program that answers private well questions, and its list of labs certified to run drinking water tests. A certified lab is the difference between a result you can act on and a number.
- Private Wells, NYSDOH
- Environmental Laboratory Approval Program, NYSDOH
Contamination sources on record in Shelter Island
NYSDEC remediation sites records 1 hazardous waste site in Shelter Island, among 1 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.
- 1
- hazardous waste siteSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
Treatment that fits the local profile
Nitrate
Point-of-use reverse osmosis; Anion exchange; Distillation
Iron
Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration
Manganese
Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis
Systems we would look at first
Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.
For nitrate
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
For nitrate
Aquasana SmartFlow reverse osmosis
under-sink or countertop, about $225
Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.
For iron
Iron and manganese oxidizing filter
whole-house, at the point of entry, about $1,800
Air-injection or greensand media; fixes staining at the source.
Free, no obligation
Get on the list for a free in-home water test in Shelter Island
No water treatment company serves Shelter Island through Well Water Nerd yet. We are signing licensed companies on county by county: they test at your tap for free, walk you through the numbers, and quote treatment only if something needs fixing. Leave your details and you are first in line. Nothing is shared until a company joins for Shelter Island, and you get an email naming it first.
Common questions
How deep are wells in Shelter Island?
The typical domestic well in Shelter Island is 53 feet deep, based on 1,211 wells reported to the state. One in ten is deeper than 87 feet.
Is there arsenic in well water in Shelter Island?
Arsenic was detected in 53% of 17 public well samples in Shelter Island, and 0% were above the EPA limit of 10 ug/L. Arsenic has no taste or smell; a lab test is the only way to know your level.
How often should I test a private well in Shelter Island?
Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.
Towns near Shelter Island
Closest first. Groundwater does not stop at a line on a map, so the next town over is a fair second opinion.
Want the numbers themselves? Download the New York dataset as CSV, every county and town, with the sources named.
Sources
- USGS Water Quality Portal: 1,425 samples in Shelter Island. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
- NYSDEC water well completion reports: 1,409 well records in Shelter Island, 1,211 domestic. Water well completion reports filed with the New York State Department of Environmental Conservation Water Well Contractor Program since 2000. Only aggregates are shown; owner names and addresses are never stored. Retrieved September 16, 2026.
- NYSDEC remediation sites: 1 regulated sites located in Shelter Island. State Superfund, brownfield, voluntary cleanup, RCRA and spill remediation sites from the New York State Department of Environmental Conservation Environmental Remediation Sites database. Retrieved September 16, 2026.
Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.